In this paper, a miniaturized microstrip square loop resonator sensor with symmetric meander open-loop arms is proposed. Based on the capacitive perturbation effect on the resonant frequency variation, the solution sensing could be implemented by this simple resonator. A compact microstrip square loop resonator probe centered @2.62 GHz is designed and good saline solution sensing with NaCL solutions ranged from 0 wt % to 0.9 wt % is demonstrated. Only trace amount of 5 μl sample is needed for this resonator sensing.